This invention relates to enclosure structures, and more particularly to such structures suitable for fixed or mobile use that employ foam sandwich panels of the type having a rigid foam core with high tensile strength inner and outer faces for high strength, light weight and superior insulation.
Recent developments in the production of foam sandwich building panels have provided an inexpensive, strong, light-weight and insulating building panel to the construction industry. The core is generally a rigid, closed cell foam of polystyrene or polyurethane. The inner and outer skins may be plywood, oriented wood fiber board, plastic, metal and the like. The skins have high tensile strength so that, when bonded to the core, they serve as the flanges of a girder with the core serving as incompressible web. The result is a rigid broad panel that can take heavy loads without other supports. These panels have been used effectively with ordinary wood timber frames by nailing the panels to the frames.
This type of construction, using oriented fiber board (OFB) panels has become an industry standard. The panels are faced inside with gypsum board and outside with weatherproofing material. The panels permit spanning large areas without intermediate frame support. Vertical walls are generally four inches thick and horizontal, load bearing floors and roofs are generally six or eight inches thick depending on unsupported span length. The result is a well-insulated heavy building, but the costs are high because the frame involves labor and materials similar to convention construction with the foam panels exceeding the cost of conventional materials. Furthermore, the wood timber framing that joins adjacent panels has fibers that run parallel to the panel edge. Stresses transferred from the panel to the frame tend to pull the frame fibers apart, i.e. the frame joining panels has longitudinal, but not transverse strength, and it is the transverse strength that maintains the relative position of the panels.
Consequently, this type of construction has not found favor for transportable structures such as mobile homes, railroad or truck bodies or inexpensive prefabricated buildings that are subject to irregular lateral forces.